Apparatus for enlarging a linear graph



y 12, 1955 R. J. HERBOLD APPARATUS FOR ENLARGING A LINEAR GRAPH 3Sheets-Sheet 1 Filed March 4, 1952 Rob c J. Hiii ill.

R. J. HERBOLD 2,712,694

5 Sheets-Sheet 2 SELSYN APPARATUS FOR ENLARGING A LINEAR GRAPH July 12,1955 Filed March 4, 1952 wk 8M- Roberi J. H gfigffd. Q?

July 12, 1955 R J HERBQLD 2,712,694

APPARATUS FOR ENLARGING A LINEAR GRAPH Filed March 4, 1952 3Sheets-Sheet 3 INVENTOR.

Robeg I Herbolcl.

Robert J. Her-hold, Denver, (10110., asslgnor to Lafayette M. Hughes,Denver, Colo.

Application March t, 1952, Serial No. 274,814 6 Claims. 33*23) Thisinvention relates linear graph or curve.

Various types of linear graphs or curves may manually, mechanically orphotogr onically, but l tions of the recording equipment may requirethat graph be very small in dimensions and thereto to inspect and iiterpret unless it can be magniz" raphy is a standard method ofenlarging, desirable to use this method to enlar e an oscillogr screenrecord or" a complex wave design, for example. The oscillograph lightspot on the screen is comparatively large, and a photographic record ofits movement is ordinarily made on a small film to produce a reducesized image that is sharp. i l made to enlarge that film g to appr. usfor enlarging rn' ital a the cult is lh itl ically, of course the imageline itself is broadened as Well as having its xand y-climensionsexpanded. The same considerations apply to the magnification of othertypes of mechanically or manually produced raps The primary purpose ofthis inv n is to provide an apparatus for expanding or yang thecoordinates of a linear graph without broadening or e Width of the graphline itself.

A further object is to provide apparatus of this be whereby thedirections of the curve relative to .rand y-coordinates of a linearcurve may be varied u- 1 ly if. either to different magnifications orequally, so as to accentuate either of the coordinates relative to theother or to magnify both to required selected e ents.

Another object is to provide apparatus of this type in which thecoordinate expansion of the curve may be made substantially uniform asto one axis, and to a suitable extent under the control of the operator,while the other axis expansion of the curve is automatically effected bymoving a stylus in a timed relation with the follower and through adistance which may be independently varied.

A 'urther object is to provide mechanism for reproducing at a desiredmagnification the movement or" a graph follower which is moved laterallyby manually operated mechanism to follow a uniformly moving g ab, andwherein the reproducing stylus is moved automatically by and in timedrelation with the follower movement, and the relative movements of thestylus ant the record strip may be varied to vary the magnification indeendently as to either coordinate of the curve. Further objects will beapparent in the foilowin g disclosure.

in accordance with this invention, l have provi a apparatus whereby anoriginal curve or linear graph to be magnified is mounted for a uniformmechanical movement in the direction of one coordinate axis a naph,while it is viewed by the operator through a microscope stem @lliceFetter-"sled Jul" 1 95 arranged to marl; the strip as it moves. Thestrip movement is selected to be proportional to, and usually severaltimes greater than, the graph movement so that this move ment of thestrip relative to the sylus serves to magnify the graph as to one graphcoordinate. The stylus is moved mechanically in a selected proportionalratio to the lateral microscope movement, as determined by the operatorscontrol. This stylus movement is preferably effected by means of aSelsyn generator-motor set, so that the lateral movement of the stylusis in a direct relation to the microscope movement. Thus the compoundrelative movement of stylus and strip provides a magnification of theorigi: ii graph as to either or both coordinates and the width. orsharpness of the final graph is not affected by the magnification.

Referring to the of the invention:

Fig. l is a top plan view, partly broken away and with 'novcd, of boththe graph viewing and the records of the apparatus is a somewhat dia .1022 of Fig. l;

' a vertical section taken approximately on the f Fig. 2;

i is a vertical section taken on the line 4-4 of drawings illustratingone embodiment aromatic end view taken moving the film graph.

The preferred form of apparatus shown in the drawings comprises a devicefor scanning a film graph and making an enlargement, or even areduction, in either the xor y-axis coordinate, or both, in any desiredrelative proportions. To this end, and as shown primarily in Fig. l, asuitable microscope 2 has its cross-hairs or other loca ng featuremovably mounted on a slide 3 and arranged to be focused on and followthe graph as the latter is moved uniformly in one direction. Themovement of the micro scope is employed to control a stylus or scribingdevice which produces the final desired curve. The s"dc 3 is movedlaterally relative to one axis, such as the y-axis coordinate of thegraph, by a racl; and pinion device 2-, while the graph is being movedat a steady rate lengthwise or along its x-axis coordinate. Themicroscope di' 'ing rack is secured at one end to the slide 3, and itspinion is driven manually by means of hand operated mechanism, such as aslow speed crank dev'ce 5 connected through gearing with the pinion. Afast speed crank mechanism 6 likewise operated manually is connected tothe same pinion, and these two cranks are so arranged that they may movetle microscope either slowly or rapidly, so that the crosshairs may hemade to follow the curve of the film graph as the latter is moved longitdinally beneath the microscope.

graph 1, which may be on a photographic film ate, for example, issuitably sort d a carrier ounted to be moved by a further it an piniondevice cc. an rotated by 'ating through 'on gear unit ll. that unit mayhr e its g Ion varied suitably, such by chat or the rotational speed ofthe varied, such as by means or" a va. motor. Thus the graph film on itsdriven lengthwise of one coordinate at a beneath the cross-hairs of themicroscope. v microscope is moved laterally relative to the diion of thefilm graph by cans of operated cranks 5 and (a. The t is for an accuratemovement of the telescope where the graph curve is not too steep, whilethe high speed gear mechanism 6 serves for a very quick motion of thetelescope where the curve is approaching parallelism with the y-axis.

The cranks 5 and 6 operate through a gear train 12 which is connected torotate a Selysn generator 13, and that generator (Fig. l) is arranged tocontrol the movement of a companion Selysn motor 14 that governs thelateral movement and speed of a stylus that shapes the final enlarged orrecord curve. The film carrier or slide 7 may be moved by its drivingmotor through an over-riding clutch 15, shown in Fig. 6, which isadapted to permit positioning the film graph 1 relative to themicroscope cross-hairs at the start, and which will provide forreturning the slide 7 to a starting position at the end of a scribingoperation. This over-riding clutch thus permits setting the slide asdesired without disturbing the driving motor ll) and its variable speedmechanism Ill. The film carrying the graph 1 is illuminated by asuitable electric lamp 16 (Fig. 4) positioned beneath the slide 3 andmovable therewith.

The recorder or scribing mechanism comprises a strip 29 of paper orother suitable material (Fig. 3) on which the enlarged or magnifiedgraph is to be made. The graph ll may be very long in one direction,particularly he x-axis coordinate, and the paper strip is made of asuitable length and width to accommodate the magnified curve. This longand narrow strip of paper is driven lengthwise by a suitable roller 21arranged for frictionally driving the same. The roller is driven by agear train 22 which is in turn driven by a constant speed motor 23through a variable speed mechanism comprising a friction disc 24 drivingan adjustably positioned roller 25 connected to the gear train. By.ianually varying the position of the driven roller radially over theface of the friction disc, the speed of linear movement of the recordingpaper strip 29 is varied. This speed determines the x-axis dimensions ofthe curve, since a lower speed movement of the paper relative to themove ment of the graph 1 would serve to compress the curvelongitudinally, while a higher speed would stretch the curve as to thatx-coordinate.

The recording stylus that is adapted to mark on the moving strip may beof various types, such as an inking pen or a pencil of light Working ona sensitized photosensitive filrn. I prefer to make the desired recordcurve by means of an electrical stylus adapted to provide an electricspark which operates to perforate the moving strip at closely spacedintervals and to leave a visiole record of the row of perforations. Thisspark may be provided by a movable metal stylus 25 (Figs. 1, 3 and 5)having a point or sharp edge arranged close to the paper and adapted totransmit a spark through the paper. This metal stylus is freely moved bymeans of a sensitive supporting and guiding mechanism, and it receivesthe electric charge from a rod 27 arranged laterally close to the stylusbut not touching and interfering with its movement. The rod 27 extendstransversely of and perpendicular to the direction of paper stripmovement and parallel to the plane of the paper. The stylus is mountedto move parallel with the axis of the rod 27 so that the distancespacing of the stylus 26 from both the rod and the paper remainsconstant. lieneath the paper is a wire or rod 28 parallel to the rod 27adapted to act as the other terminal of the double spark gap formed bythe stylus located between and slightly spaced from the rods 27 and 23.The electrical energy is supplied by a suitable high voltage generatorand condenser with an interrupter. Thus a succession of sparks jumpingbetween the movable stylus 26 and the upper rod 27 and the lower wire orrod 2% serves to burn a series of holes through the moving paper. Theinterrupter operates at such a rate that the perforations are very nism5 close together and form what may be considered a substantiallycontinuous graph or trace 29 (Fig. 1).

The metal stylus 26 is preferably shaped as a double convex disc havinga sharp circular periphery. The stylus is delicately suspended on astrong endless thread 3' 3 (Figs. l and 5) which is suitably tensionedby a spring 31 so as to hold the stylus at the correct distance from butclose to the paper 29. This thread is lead by suitable pulleys and woundone turn around a drum 32 arranged to be rotated in either direction bythe Selsyn motor Zl iwhich is electrically connected to and movable insynchronism with the Selysn generator 13 governed by the microscopemovement. a gear train 33 (Fig. l) which governs the motion of thestylus 25 accordance with the multiplication of microscope motionprovided by the apparatus. Because of the ep-up gear train 12, theSelsyn generator 13 is rotated through many turns for a very slightlateral motion of the microscope, and the Selsyn motor 14 is driven inangular synchronism with the Selsyn generator. Therefore the rotarymotion of the Selsyn motor 14 is to he stepped down by the gear train 33(Fig. l) to the desired extent of reduction of speed for the stylus 26,so that one may get any desired ratio of y-axis enlargement for thegraph. This step-up and step-down gear system reduces any error in thegraph shape that might be caused by a lack of synchronization of the twoSelsyn elements. Thus the Selsyn motor 14 moves the spark gap stylus 2t:delicately to that magnifying extent which is required to enlarge thefinal curve according to the lateral or y-axis movement of themicroscope, while the movement of the paper strip provides the .r-axisenlargement. Qne may vary the speed of the gear train 33 by changing thegears or by the use of a suitable variable drive. Thus an 8 to 1enlargement, suggested as an example of this curve enlargement for bothcoordinates, may be varied as desired. In this way any enlargement ofthe curve along its 25- and y-axes nay be accomplished without enlargingthe thickness or materially changing the shape of the curve itselfexcept as is caused by manual variation in the y-axis movement of themicroscope which is under the operators control. it will be appreciatedthat a sine Wave curve, for example, having definite y-coordinates adefinite wave length may be stretched out to leave the maxima and minimapoints of the wave at the same or at greater y-elevations so that eitheror both of the xand y-axis coordinates may be magnified to the sameextent or differently.

In view of the above description of the major features of the invention,it will be appreciated that various details of construction may beemployed such as those illustrated in the drawings. Referringparticularly to Figs. 1 and 4, the microscope 2, which is of suitablepower, is mounted vertically on a slide 3 held between slide ways 4% onthe top of a table ill. That table is pivotally mounted at 42 on an arm43 carried by the framework of the apparatus, so that the table may belifted into the position shown in dotted outline in Fig. 4- and provideaccess to the film graph carrier 7 therebeneath. When the table 41 islowered into an operative position, its forward end is supported on across bar 44 or other suitable device carrying the front ends of slidesupporting rods 8 and so prevents interference by the table with themovement of the slide or graph carrier 7. The Selsyn generator 13 andassociated gear mechanism 12 are mounted on the tiltable plate 41.

The film may be suitably mounted on the sliding carrier 7. it is shownin Pig. 4 as being held between a lower horizontal glass supportingplate 45 and an upper glass plate 47 resting on the film which serve tohold the film smooth and immovable relative to the carrier 7. The plate41, the slide 3 and the plates 46 and 47 are transparent or are providedwith cooperating holes of suitable size so that the microscope may viewthe film 45 and The Selsyn motor 14 has,

anaestthe latter 1 ay be illuminated by the lamp carrier 7 has dependinglugs 42; provided cylindrical bearing openin therethrough and soarranged that the carrier pla e 'l' may slide horizontally on the twoparallel cylindrical rods The left hand lug is connected to the rack bar3 slidably mounted in a boss on the box the drive mechanism it and motor13. The gear 5b of the reduction gear unit ll which drives the rack baris suitably mounted in bearings and is driven by another gear on the endof the shaft of the driving motor al The associated gears of themechanism 1ft may be exchanged for other suitable The metal withparallel gears so as to vary the speed or the rec oar drive, or ifdesired, the motor may a sui 'le variable speed electric motor arrangedto drive t e rack bar at a desired uniform rat This driving rate is ofcourse very slow and is so controlled that the operator will have ampletime for viewing the graph 1' moving the microscope laterally asrequired to keep the cross-hairs of the microscope on the graph 1 whilethe graph c' er 7 is moving the graph film lengthwise as indie a in Fig.l

The mechanism for moving the laterally of the film graph comprises 1) ofthe rack pinion devi d on a shaft 57 micr scope slide 3 a rack bar (Fig.e and a meshing pinion and driven through a suitable d to permit adjustThe shaft .7, which is suitably meat of the n. oscop mounted, has a gearmeshi g with a small gear as fixed on a stub so which is con 62 carryingthe crank handle [hus manipulation of the cranl; handle e serves torotate the comparatively fast speed reduction mec iistn 6d drive themicroscope slide 3 laterally at a manually controlled rate. The othercrank is connected through a small gear 6 with a larger gear 65 fixe ona short stub shaft which further carries a small gear e driven t by andintermeshing with the large gear ll. Thus this further train ofreduction gears connects the handle with the reduction gears controlledby the crank 6 and gives a still slower speed motion of the microscopeslide. Hence the crank s may be conside as a comparatively fast speeddrive while the other es a much slower speed. it is to be appreciatedthat the operator is viewing the graph through microscope, and that tomaintain the cross-hairs of the microscope on a very small graph 1 willrequire a minute movement of the microscope. The operator, having hishands on both of the cranks 5 and 6, can therefore, after a littlepractice, move one or the other of the cranks slowly or rapidly tomaintain that cross-hair contact.

cted to a larger gear scope and in that way const" drive me hanisrn, sothat the Seisyn generator rotates ough a large an le or even many turnsfor a very slight movement of the microscope. As understood by thosefamiliar with Selsyn mechanisms, the angular movement of an armature fthe generator 13 will be almost exactly duplicated by a similar angularmovement of the Selsyn motor which controls the scribe recordingapparatus.

The Selsyn or servomotor system may be of any suitable type. general, itcomprises an alternating current generator in (Fig. and synchronousmotor 1 5 in which the stators are each built like a three phaseinduction motor. The rotor of each has a bobbin type of core providedwith a single winding energized from a single phase source of alternat Icurrent, The two rotors are connected in parallel with a source ofalternating current conducted through suitable slip rings. The threecorresponding t ps of the y windings of the two stators are connectedtogether. in its operation, the rotor of the generator provides analternating field cutting the windings of its stator and thereby inducesa secondary current in that winding which sets up a corresponding pola'y in the stator of the motor 314, so that rotor of that motor has aninduced field which is ame as that of the generator 13. Hence the rotorof syn hronous motor 14 will tend to stand at the same -eiative to itsstator as does the rotor of the gencrate-r and since the hi. F. that isinduced in each winding is equal, there is normally no circulatorycurrent. if, however, the rotor of the generator 13 is turned through agiven angle, there will be a phase displacement between the E. F.induced in the stator of the the the l'vl transmitter and that in thereceiver stator of the motor i i, and the resultant circulatory currentbetween the two stator windings will pull the rotor of the receiving setid to the same angular position as that of the rotor in the transmitterset 13. Hence the rotor of the motor 114 will make the same angular orrotative movement as does the rotor of the generator The synchronousactor 34 drives the Winding drum 32 through a reduction speed gear train33 that is suitably mounted in the box 68 (Fig. I). This gear train hassuch a drive ratio that it will move the stylus 2-6 at the required 1 ofmagnification as compared with the m' -oscope movement. The drum 32 isturned in opposite directions in accordance with the movement of therotor of the generator 33, and this serves to move the stylus 26 backand forth as the paper 24: is drawn therebeneath in the direction of thearrow (Fig. 1).

The electric spark for the stylus may be suitably generated. As shown inFig. 5, a suitable transformer 79 has its secondary connected directlyto the rods 27 and 25, which are properly spaced close to the discshaped stylus 26 so that the spark will jump to the stylus between therods an. con equently t ough the paper 29 therebetween. The p nary ofthe transformer is in series with an interrupter 72 in which the movablespring pressed arm or" the make and break contact is lifted about itspivot 73 by 2 cans of a cam 74 of suitable shape. This cam is rotated bya constant speed electric motor 75, the speed of which is adjusted toinsure that the spark perforations in the paper are spaced far enoughapart to prevent cutting the paper and yet close enough to provide afairly continuous curve 29. The spark voltage can be varied by a voltagedivider comprisin a suitable resistance 76 and a movable contact arm '77arranged as illustrated in Fig. 5. The two rods 2'7 and 28 are suitablymounted on insulator posts and 79 and various precautions will be takento insure satisfactory operation of the spark circuit. The transformermay be of such a type as to give 10,060 volts, or as desired.

The paper strip 2f may be drawn paper roll (Figs. 1 and 3) by means ofthe driven roller 21 above which is a spring pressed roller 31 arrangedto provide the necessary friction. The roller 21 is suitably mounted onsupports and has a large gear 32 keyed on its shaft which is driventhrough the reduction speed gear train 22. This train comprises a drivegear 84 (Figs. 2 and 3) meshing with a smaller drive gear 85 on the endof a long roller 36. This roller 86 frictionally engages the narrowdrive roller 25 pivotally carried on a slide arm 83 which is threaded onthe screw shaft 8 and moved thereby parallel with the face of thefriction disc 24. The shaft is suitably adjusted by a dial on its outerend. These parts are so arranged that the drive roller 25 may be movedradially from near the center outwardly toward the periphery of thedrive disc E i while remaining in rotative contact with both the roller86 and the drive disc. The drive disc is suitably mounted on a shaftcarrying the pulley connected by a belt It to the drive pulley of theelectric motor 23. A dial Q2 on the end of the screw shaft 39 serves formoving the intermediate friction roll 25 and holding it in any desireddriving position. Thus the speed transmitted to the paper strip 2t} fromthe constant speed electric motor through the reduction gears 22 may bevaried accurately as desired. A variation of the position of forwardfrom a the drive roller 25 accordingly serves to change themagnification of the x-coordinate of the curve 29 (Fig. l), and thiscontrol is entirely independent of the control of the y-axismagnification. The later may be varied by changing the gears of thereduction speed mechanism 33 (Fig. 1) and/or the gears of the gear train12. The gear train 12 governs the rotational movement of the rotor ofthe Selsyn generator 13, and the gear train 33 governs the reduction inrotor motion of the drum 32 which the synchronous motor 1- drives.

The overriding clutch 15 may comprise, as shown in Fig. 6, friction pins93 mounted in axially aligned holes in the gear 5% and pressed by meansof springs 94 against the face of the gear 95 which is driven by thegear 52 on the shaft of the motor ill. The gears 50 and 95 are freelymounted on the shaft 96 so that the power from the motor ltl istransmitted to the rack bar 49 only through the friction drive. Thispermits the rack bar and the carrier '7 to be moved relative to themotor to any desired position. A similar construction may be employedfor the clutch 58 which connects the microscope rack 55 to the Selsyngenerator 13 and the hand operated levers 5 and 6. it will beappreciated that various other mechanical constructions may be employedin this apparatus and suitable modifications made to accomplish thepurposes above described.

The operation of the device will be apparent. The operator places on theslide or carrier 7 the photographic film 45 carrying the graph 1 whichis to be magnified. By means of the two slip clutches 15 and 58, thecarrier and the microscope are adjusted to positions where themicroscope is exactly aligned with the beginning of the curve 1, such asat the right hand end. Previously, the various speed mechanisms havebeen adjusted to give the desired magnification of both the xandy-coordinates of the curve, such as an equal magnification of eighttimes. Then, while the operator manipulates the cranks 5 and 6 so as tomaintain the cross-hairs of the microscope exactly on the curve, themotors 10 and 23 controlled by the switch 93 (Fig. 5) are started inoperation and thus the film carrier '7 is gradually moved toward theright. As the operator adjusts the position of the microscope by thecranks 5 and 6 and holds the crosshairs on the curve 3., the Selsyngenerator 13 is rotated in accordance with the movement of themicroscope slide and this causes the Selsyn motor 14 to move through thesame angular distance and in the same rotative direction and thusthrough its reduction speed mechanism 33 to move the stylus 26 laterallyof the traveling paper Zll. The transformer and interrupter circuitcauses a succession of spark perforations and discolorations to appearas the line 29 on the moving paper. The x-aXis enlargement is accuratelydetermined by the predetermined relationship of the speeds of the filmcarrier 7 and the paper strip 20. The y-axis enlargement of the curvedepends upon the relative gear ratios of the two Selsyn mechanisms l2and 33. The shape of the curve is governed by the operators skill, butby adjusting the speeds of the paper and film carrier driving mechanismswithin his capabilities, the operator will be able to follow the curveaccurately with the microscope, and the deviations from the originalcurve will be so minute as to be negligible. There are many types ofcurves produced as oscillograph or photographic records which requireamplification for careful study, and this apparatus will amplify thecurve as much as is within the capacity of the microscope and theability of the operator to maintain the microscope bearing correctly onthe graph image. Various other advantages will be apparent in thisconstruction.

The above disclosure is to be interpreted as describing a preferredembodiment of the invention and not as imposing limitations on theappended claims. it, however, will be appreciated that various changesmay be made in this construction. The microscope may be replaced by anysuitable type of viewer or a follower having a line point adapted to belocated accurately on the linear graph. The relative movement of thisfollower or viewer and the graph to be reproduced or enlarged as toeither or both coordinates serves to control through a suitableservomotor system the relative movement between the recording stylus andits associated strip, so that the record mark produced by the styluswill be related to the original curve with either an equal or adifferent magnification as to the two coordinates. Various equivalentconstructions will accomplish this general purpose within the scope ofthis invention.

I claim:

1. Apparatus for making a linear record related to a linear graphcomprising a movable support for the graph, p wer operated mechanism formoving the graph support in the direction of one coordinate at a uniformrate, a laterally movable graph follower, manually operated mechanismfor moving the follower laterally in the direction of the othercoordinate so that it may follow the moving graph, a record strip, meansfor supporting the strip for an independent linear movement, a laterallymovable stylus mounted for marking the strip, power mechanism for movingthe record strip in a direction related to the graph movement and at auniform rate independent of and dilerent from that of the graph movementwhich etermines one coordinate magnification of the graph, andindependent mechanism controlled by the lateral movement of the followerfor moving the stylus laterally relative to the moving record strip to avariable distance and at a rate coordinated with but different from thegraph follower movement which determines the second coordinatemagnification, so as to produce a linear record related to the graph inwhich the two coordinates of the graph are independently varied in therecord to predetermined proportions.

2. Apparatus for making a linear record related to a linear graphcomprising a movable support for the graph, adiustable power drivenmechanism for moving the graph support at a uniform variably selectedrate in the direction of a first coordinate, a graph follower mountedfor lateral movement in the direction of a second coordinate, manuallycontroiled mechanism for moving the follower laterally so that it willfollow the moving graph, a record strip, a support mounted for movingthe strip in a direction related to but independent of the movement ofthe graph support, power driven adjustable mechanism for moving therecord strip at a uniform but variably selectable rate which determinesthe magnification of the graph relative to said first coordinate, astylus, a stylus support independent of the graph follower whichprovides for lateral movement of the stylus to mark the record strip,power mechanism automatically driven by and in timed relation with thefollower movement which causes the stylus to move laterally in thedirection of the second coordinate and mark the moving strip, and meansfor varying the relative rates of movement of the follower and stylus soas to provide a predetermined and independent magnification of the curverelative to the second coordinate.

3. Apparatus according to claim 2 in which the follower comprises amovable support, a microscope mounted thereon in position to view thegraph and manually operated alternately employed low and high speedmechanisms connected to move the microscope support for following thegraph.

4. Apparatus for making a linear record related to a linear graphcomprising a movable support for the graph, power operated mechanism formoving the graph support in the direction of a first coordinate at auniform rate, a laterally movable graph follower, manually operatedmechanism for moving the follower laterally in the direction of a secondcoordinate, a Selsyn system including a generator having a rotor,mechanism connecting the rotor with the graph follower so that theangular displacement of the rotor varies with the graph followermovemeat, a record strip, means for supporting the strip for a linearmovement independent of but related to the graph movement, a stylus, asupport providing for lateral movement of the stylus for marking thestrip, a Selsyn motor in said system having a rotor whose angularposition is governed by the generator rotor, mechanism connecting themotor rotor with the stylus for moving it, said Selsyn connectedmechanisms providing a second coordinate magnification of stylusmovement relative to that of the follower, and power mechanism formoving the record strip at a uniform controlled rate different from andindependent of the graph movement which provides a first coordinatemagnification of the curve in the direction of strip movement.

5. Apparatus according to claim 4 comprising a stepup gear mechanismconnecting the Selsyn generator rotor with the follower moving mechanismand a step-down gear mechanism driven by the Selsyn motor rotor whichmoves the stylus, one of said gear mechanisms providing for a change ofspeed or" the stylus relative to that of the follower for varying thesecond coordinate magnification.

6. Apparatus according to claim 4 comprising a lower electricalconductor mounted beneath and extending laterally of the record strip,an upper electrical conductor above the strip parallel with the lowerconductor, the

stylus being an electrical conductor traveling close to the upperconductor and the record strip and serving to transmit a spark from theupper to the lower conductor through the strip, and an electricalcircuit to provide said spark including an interrupter and motormechanism for interrupting the circuit and causing a spark, the speed ofsaid motor mechanism being adjustable for varying the rate of sparkproduction to cause the sparks to perforate the record strip at spacedintervals.

References Cited in the file of this patent UNITED STATES PATENTS

